Recovery of nickel from dole nickel



A. WESLEY ET AL 2,442,629 RECOVERY OF NICKEL FROM IDLE NICKEL ELECTROPLATING BATHS AND THE PRODUCTION OF AN IRON-NICKEL MASTER ALLOY Original Filed 001:. 8, 1943 CONTROL CHART ELECTHOLYSIS WITH STEEL ANODES NICKEL RECOVERY PERCENT 0 100 zoo 500 400 500 e00 700 mans nouns pan GALLON Aunasw wnszlmx 2mm .nmsou ROEHL INVENTOR.

ATTORNEY.

Patented June 1, 1948 RECOVERY OF NICKEL FROM IDLE NICKEL ELECTROPLATING BATES AND THE PRO- DUCTION OF AN IRON-NICKEL MASTER ALLOY Andrew Wesley, Plainfleld, and Edward Judson Roehl, Little Silver, N. J., assignors to The International Nickel Company, Inc., New York, N. Y., a corporation of Delaware Original Application October a, 1943, Serial No. 505,4. Divided and this application December 11, 1941, Serial No. 790,968. In Canada October 5, 1943 The present invention relates to a process for recovering nickel and producing an iron-nickel alloy suitable for use in steel making.

The problem of recovering nickel from idle nickel electroplating baths is one for which those skilled in the art had no solution prior to a comparatively recent date. Less than a year ago many experts in the art admitted that they were unable to suggest an economic process for recovering nickel from nickel electroplating baths which. due to the emergency then existing, were idle. These experts estimated that the idle nickel electroplating baths contained about 200,000 pounds of nickel which could be employed advantageously in the furtherance of the war eflort. However, none of the experts knew of a satisfactory process which could be fitted into the existing equipment of electroplating plants to produce a salable nickel product economically.

One idea that had been suggested was to evaporate the idle nickel electroplating solution and then roast the impure nickel sulfate to impure nickel oxide. However, some undisclosed use for the impure nickel oxide would then have to be found and no expert could suggest a use. Another suggestion was to precipitate nickel from the idle nickel electroplating solution by the addition of sodium carbonate followed by the conversion of the nickel carbonate so produced to the oxide or some other form. However, all of the experts readily agreed that all the suggested solutions to this problem were not feasible and practical, primarily for economic reasons.

We have found that nickel can be recovered economically from idle nickel electroplating solutions by electro-deposition as an iron-nickel alloy suitable for use in steel making and similar metallurgical operations. It is well known that many attempts have been made to electro-deposit iron-nickel alloys. However, most of the processes suggested for the production of iron-nickel alloys involved careful operation of the electrodepositing process with special attention either to the composition of the electrolyte or to the relative areas of the iron and nickel anodes. Thus, for example, Burns and Warner disclosed a process in U. S. Patent 1,837,355 for electrodeposlting nickel-iron alloys in which an anode of nickel, a second anode of iron and a cathode are immersed in an electrolyte composed of nickelous sulfate, ferrous sulfate, nickelous chloride, ferrous chloride, sodium sulfate and boric acid. The composition of the electrolyte or the proportion of the constituents of the Burns and 4 Claims. (Cl. 204-43) Warner electrolyte is adjusted so as to make the cathode potentials of the nickel and iron substantially equal over the Operating portion of the current density range. Burns and Warner prefer to employ a current density of about, 4 amperes per square decimeter or about 37, amperes per square ioot, employing anodes which provide a ratio of anodic surfaces of about nickel to about 15% iron.

In U. 8. Patent No. 2,131,427 Crowder discloses a process for producing an iron-nickel alloy in which the nickel content does not substantially exceed about 5%. According to Crowders process a special electrolyte is employed containing ferrous sulfate, nickel sulfate, hydrofluoric acid and sodium fluoride.

M. P. Thompson reviewed the effect of iron on the electro-deposition of nickel in an article published in the Transactions of the American Electrochemical Society, volume XLIV, pages 359-396 (1923). Of course, Thompson was not concerned with the production of a nickel-iron alloy but in determining the effect of small amounts of iron, of the order of 6 or 7%, upon the characteristics of the electro-deposited nickel. During his review, Thompson studied the work done by Toepfler who found that, in general, a greater proportion of iron is deposited in the alloy than is present in the solution. Glasstone and Symes, in an article published in the Transactions of the Faraday Society, volume 23, pages 213-226 (1927), found that the amount of iron in an electro-deposit increases rapidly 'with increasing current density until the maximum is reached, after which further increase of the current caused the proportion of iron in the deposit either to remain constant or to decrease.

We have found that the processes of Burns and Warner and Crowder and the disclosuresand investigations of Thompson and Glasstcne and Symes do not provide the solution to the problem of recovering nickel from idle nickel electroplating baths and producing a master alloy suitable for use in steel making and analogous operations at an economic cost. As a matter of fact, operating according to Burns and Warner or Crowder would defeat the purpose of our process.

It is an object of the present invention to provide a process for recovering nickel from idle nickel electroplating baths in an economically practical manner with equipment readily available in the average nickel electroplating plant.

It is another object of the present invention to provide a process for producing an iron-nickel master alloy suitable for use in steel making and analogous metallurgical operations.

It is a further object of the present invention to provide a process for electro-depositing an iron-nickel master alloy containing about 50% nickel.

The present invention also contemplates aprocass for recovering nickel from idle nickel electroplating baths employin solelyv ferrous anodes substantially devoid of nickel or containing less than about 10% nickel.

The present invention also contemplates the provision or a process dor recovering nickel from aqueous solutions containing soluble nickel salts and iron salts employing solely as anodes ferrous anodes substantially free from nickel or containing at most about 10% nickel.

Other objects and advantages will become ap parent from the following description taken in conjunction with the drawing which is illustrative of the current density control exercised during the electro-deposition of nickel from an aqueous electrolyte employing solely ferrous anodes substantially devoid of nickel or only containing a small amount of nickel, say not more than about 10%.

Broadly stated, the present invention provides for the electro-deposition of an iron-nickel alloy containing more than 5% nickel particularly from idle nickel electroplating baths which may contain, in addition to the usual nickel electroplating salts and the usual bufl'ers, the conventional brightening agents and similar addition agents employed in the art to produce bright nickel electro-deposits and to reduce pitting and the like. In the present process it is not necessary to employ nickel anodes and, as a matter of fact, it is preferred to employ only ierrous anodes such as steel anodes or iron anodes. The steel anodes preferably are of plain carbon steel but may contain small amounts of alloying ingredients. Accordingly, low alloy steels may also be used as anodes.

According to the present invention the electrodeposition of the nickel-iron master alloy is carried out at a pH of about 2.0 to about 5.0 but preferably at a pH of about 4.0 to about 5.0. That is to say. if the solution from which the ironnickel master alloy is to be electro-deposited has a low pH such as a pH of about 2.0, it is not necessary to adjust the pH before starting the electrodeposition of the nickel-iron alloy. However, as electro-deposltion proceeds it is preferred to hold the pH of the solution between a pH of about 4.0 and a pH of about 5.6.

The composition of the electrolyte from which the iron-nickel master alloy is to be electro-deposited is not important provided the nickel is present as a water soluble nickel salt. As those skilled in the art know. conventional nickel electroplating solutions generally contain the nickel in the form of its chloride or sulfate. However. it is not necessary that the nickel be present as the chloride or sifli'ate. The present process is operative even if a portion or all of the nickel is present as salts of nickel other than the chloride or sulfate. Furthermore. it is not necessary that a bufler such as boric acid be present although the presence of a bufler is necessary if a sound, solid alloy deposit is desired.

The potential employed in electro-deposition in the present process is determined by local conditions and the spacing of the anodes and cathodes. That is to say. a potential is employed suilicient to provide the current density within the limits whichhave been found satisfactory to produce the iron-nickel master alloy economically. Consequently, the potential will be employed within the limits of the equipment available to produee the current density of about 20 amperes per square foot to about amperes per square foot during the deposition of the major portion of the nickel in the solution and to produce the current density of about 45 amperes per square foot during the remainder of the deposition. As will be made clear hereinafter, the residual nickel can also be removed by operating at current densities or about 5 amperes per square foot. However. the potential employed is only that necessary to produce the current density desired and is not controlled with respect to the composition of the electro-deposit.

The cathode may suitably be a ferrous strip such as plain carbon steel and the like from which. if desirable. the electro-deposited ironnickel alloy may be stripped. On the other hand, if so dwired, the electro-deposited iron-nickel alloy need not be stripped from the cathode. In any event, after the electro-deposition has been brought to a conclusion, the deposit is washed, dried and melted or further treated to provide the alloy in a suitable torm for use in steel making and analogous metallurgical operations.

In order that those skilled in the art may have a better understanding of the novel process. the i'ollowing example is illustrative of the recovery of nickel from an idle nickel electroplating solu-' tion. The solution contained nickel in the following form and amounts:

Oz./gallon GrJllter l sulfa 40 300 6 10 4 30 the nickel originally in the bath had been re-.

moved as was determined by analysis. During this period a total of about 300 ampere hours per gallon of solution had been passed through the cell. During the next hundred ampere hours little nickel was recovered as is readily recognized by examination of curve I in the drawing.

That is to say, curve I is practically parallel to the abscissa for the period during which 300 to 400 ampere hours per gallon were passed through the solution. The current density was then lowered to about 5 amperes per square foot of cathode area and nickel deposition reoccurred. When about of the nickel present in the original solution had been recovered the rate of nickel removal by electro-deposition became too low to be economically practical and electro-deposition was terminated.

The deposit obtained during this electrolysis was a nickel-iron alloy with an average nickel content of about 49%.

In further illustration of the present process 6 nickel is to .be recovered contains about 10 o'unces'of nickel per gallon, a cathode current density of about 20 to about 35 amperes per square foot is employed during the removal of the flrst'about 65% to about 70%. of the nickel originally present in the electrolyte or during the an inspection of curve II in the drawing, the rate v of electro-deposition of nickel or the recovery of nickel from the solution continued at a practical rate after the current density was raised to about 45 amperes per square foot. .7 After about 550 ampere hours per gallon had been passed through the solution, the current density was lowered to about 5 amperes per square foot of cathode area and the electrolysis continued. Electrolysis at this lowered cathode current density was equally as satisfactory as that carried out at 45 amperes per square foot of cathode area. After the passage of about 700 ampere hours per gallon of solution about 88% of the nickel present in the original solution had been recovered by electro-deposition as an iron-nickel mass having a nickel content of about 50%. The curve II of the drawing clearly shows that the rate of electro-deposition of nickel after the I current density hadbeen lowered to about 5 amperes per square foot of cathode area was almost as great as it had been during the original electrolysis period at amperes per square foot. Curves I and II of the drawing clearly show that after the rate of electro-deposition of nickel at 20 to 35 amperes per square foot drops off, the rate of deposition can be accelerated either by increasing the current cathode density to about 45 amperes per square foot or by lowering the current cathode density to about 5 amperes per square foot.

In carrying out the foregoing tests, the pH of the solutions being electrolyzed was maintained between about 5 and about 5.6 (Q); that is to say, the pH of the electrolyte during electrodeposition in the first test was between about 5.0 and 5.6 (Q) and the pH during the electrodeposition illustrated by the second example was between about 5.3 and about 5.6. A third test was carried out employing an electrolyte of approximately the same composition but having the pH of about 2.0 to about 3.0 (Q). The course of the electro-deposition of th nickel from this electrolyte is illustrated by curve 111 of the drawing. Curve III of the drawing clearly indicates that nickel recovery is less eillcient and more costly at low pH such as pH 2 to 3 (Q), than at high pH such as 4 to 5.6 (Q). However, when recovering nickel from idle nickel electroplating solutions it is unnecessary to raise the pH from pH 2 or 3 (Q) by suitable addition of alkaline reagents prior to electrolysis in view of the fact that in a practical period of time the pH of the solution rises to within the preferred range. However, when desirable, the pH of the solution from which the nickel is to be recovered may be raised to a pH within the range pH about 4.0 to about 5.8 by the addition of suitable alkaline reagents such as ammonia.

Those skilled in the art will recognize that the novel process described herein involves the use of ferrous anodes at a current density depending upon the amount of nickel remaining in the solution from which the nickel is to be recovered. That is to say. when the solution from which passage of about 300 ampere hours per gallon, or until about 3v ounces of nickel per gallon remain undeposited. Thereafter, the cathode current density either is reduced to about 5 amperes per square foot of cathode area or increased to about.

45 amperes per square foot of cathode area unt'l about to about of the nickel has been recovered by electro-deposition as an iron-nickel alloy containing about 50% nickel. Furthermore, it is to be recognized that the composition of the electrolyte is not controlled to provide critical cathode potentials as taught by Burns and Warner, nor are nickel anodes as well as iron anodes employed to obtain a critical proportion of nickel anode surface to iron anode surface. Furthermore, the composition of the bath is not controlled within critical ranges to provide a critical nickel to iron composition in the electrolyte.

Although the present invention has been described in conjunction with the recovery of nickel from idle nickel electroplating baths or solutions, it is to be recognized that the principles of the present process can be employed in the refining of nickel to recover a nickel-iron product having commercial value. That is to say, refinery liquors containing nickel and iron can be treated in accordance with the present process to recover the nickel as a nickel-iron alloy suitable for-use in steel making and analogous metallurgical operations. Furthermore, the present application has been described in coniunction with certain preferred embodiments thereof, but those skilled in the art will understand that variations and modifications thereof may be made. Such variations and modifications are to be considered within the purview of the present specification and the scope of the appended claims. Thus, for example, while it is preferred to employ ferrous alloys containing not more than about 10% of nickel as anodes in the present process, it is also possible to employ insoluble anodes. However, the use of insoluble anodes increases the potential necessary to produce the desired current density and consequently increases the cost of operation.

This application is a division of co-pending patent application Serial No. 505,446, filed on October 8, 1943.

We claim:

1. A process for recovering nickel by electrodepositing a mass of iron and nickel from electroplating electrolytes without substantially replenishing the nickel from other sources as nickel is recovered which comprises passing an electric current between an anode of ferrous material substantially devoid of nickel and a cathode immersed in an aqueous nickel-containing electrolyte having a pH between about 4.0 and about 5.6, employing a current density of about 20 to about 35 amperes per square foot until the nickel content of the electrolyte is reduced to about 3 ounces per gallon without substantially replenishing the nickel from other sources as-nickel is plated out of the electrolyte, thereafter employing a different current density of about 45 amperes per square foot without substantially replenishing the nickel of the electrolyte whereby the efficiency of nickel recovery is markedly increased 8. current density. until about 85% to about 90% of the nickel originally presentin said aqueous electrolyte has been electro-deposited with iron at the cathode to provide a nickel-iron mass eontaining about 50% nickel.

4. A process for recovering nickel by electrodepositing a mass of iron and nickel from electro-plating solutions without substantially replenishing the nickel from other sources as nickel is recovered which comprises establishing an aqueous"nickel-containing electrolyte havingfi'a material substantially devoid of nickel and a I cathode immersed in a buifered, aqueous nickelcontai'ning electrolyte having a pH between about 4.0 and about 5.8, employing a current density of about to about amperes per square foot until the nickel content of the electrolyte is reduced to about 3 ounces per gallon without substantially replenishing the nickel from other sources as nickel is plated out of-the electrolyte, thereafter employing a different current density of about 45 amperes per square foot without substantially replenishing the nickel of the electrolyte whereby the efficiency of nickel recovery is markedly increased and continuing the deposition at said diiferent current density until about 85% to about 90% of the nickel originally present in said aqueous electrolyte has been electro-deposited at the cathode as a nickel-iron deposit.

3. A process for recovering nickel by electrodepositing'a mass of iron and nickel from electroplating electrolytes without substantially replenishing the nickel from other sources as nickel is recovered which comprises establishing an aqueous nickel-containing electrolyte having 35 a pH between about 4.0 and about 5.6, passing an electric current between an anode of ferrous material having not more than about 10% nickel and a cathode, maintaining a. current density or about 20 to about 35 amperes per square foot until the efficiency of deposition of nickel at the cathode begins to decrease without substantially replenishing the nickel from other sources as nickel is plated out of the electrolyte, thereafter employing a diil'erent current density of about 45 amperes per square foot without substantially replenishing the nickel of the electrolyte whereby the emciency of nickel recovery is markedly increased and continuingthe deposition at said diflerent pH between about 4.0 and about 5.6, passingan electric current between a ferrous anode and a cathode, maintaining a current density of about 20 to about 35 amperes per square foot until the efllciency of deposition of nickel at the cathode begins to decrease without substantially replenishing the nickel from other sources as nickel is plated out of the solution, thereafter employing a diiferent current density of about 45 amperes per square foot without substantially replenishing the nickel of the electrolyte whereby the emciency of nickel recovery is markedly increased and continuing the deposition at said diiferent current density until about to about of the nickel originally present in said aqueous electrolyte has been electro-deposited at the cathode as a nickel-iron deposit.

ANDREW WESLEY. EDWARD JUDBON ROEHL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 788,064 Ramage Apr. 25, 1905 969,773 Cowing Sept. 13, 1910 2,051,433 Bosqui Aug. 18, 1936 OTHER REFERENCES 

